Laser Sensor System Scans Railway Tracks

To keep the track infrastructure safe, railway operators need to acquire many track parameters in regular intervals. Irregularities in the rail geometry can cause sudden cracks in the steel rails, since these are under high tensions. These cracks in turn can initiate domino effects, with rails and railway sleepers tearing over large stretches. An innovative optical sensor system surveys the tracks quickly and safely. A laser scanner acquires geometrical irregularities and transforms them into 3D images.

Today the state of the art in surveying a railway track infrastructure appears in camera-based systems. These systems however have a number of drawbacks: The quality of the results heavily depends on the lighting conditions, and they require a rather complex processing of image data. In addition, the image data demands a very large memory space.

In its Rail Track Scanner (RTS), Fraunhofer IPM utilizes, for the first time, a laser scanner to measure rails, railheads, sleepers, and the rail bed. The specific optical design allows the scanner to be mounted just 1.2 meters above the rail bed. The device scans the tracks transversely to measure vehicle movement at a track width of some 1.7 meters. With up to 2 million single measurements per second, the instrument generates up to 800 profiles, providing a detailed three-dimensional image of the tracks and the infrastructure that is associated with them directly. Out of the cluster of points generated, appropriate algorithms extract parameters such as distance, height, and tilt of the rails, as well as the exact geometry of the railheads. These parameters then are compared with set values. The scan frequency can be adapted to the respective task. Topographic structures and deviations are identified at an exactness of less than 1 mm.

The scanner is the size of a shoebox and thus can be mounted to any rail vehicle. Thus, the RTS offers a cost-effective option to survey the rail infrastructure automatically without the need to acquire a specific measurement vehicle. Utilizing an eye-safe infrared laser (class I), the scanner can be deployed in the public space without any restrictions. The instrument, which will be introduced to the public at the Innotrans trade fair in September, will be utilized by Swiss mobile mapping services company iNovitas to survey narrow-gauge lines in Switzerland.

In India , a practice is followed , whereby for the high speed passenger trains, a pilot engine runs ahead of the train to ensure that there is no track fault or any other obstruction ( natural landslides or man made obstructions ) on the track for the following train.

If such pilots ( autonomus - like those drones) are run ahead of every train a majority of possibile accedents can be avoided.

A couple years ago I saw a panel van transiting a local highway with cameras pointed every which way. Curious about what was being done, I caught up to the van and it was some sort of camera based highway maintenance scanner, that would look for potholes and other issues. No idea if it was a service some agency had contracted, or just an outfit out trying to generate business.

This is simialr to the Lidar services that companies like mine use, to document the physical environment and ensure adequate transmission line clearances to vegetation, terrain, and buildings. From what I understand it is very expensive per mile of line, and the datasets are enormous. The level of detail is quite good, although I don't have any resolusiton or accuracy specs.

Also, if every train had this device, there would be frequent samples and therefore the ability to detect trends - a certain parameter that deteriorates over time could be detected before it was actually outside of boundaries.

I was just wondering if such scanning system be fitted on all railway engines and enables the drivers to forsee any fault in the track system before the train passes over the track.

Such system will need suitable modifications to have a lase system beaming ahead in an inclined angle to be able to see the track ahead of the train and generate alert if it finds some problem with the rails, the sleepers or the track base.

Such system will be very useful in avoiding accidents due to sudden track failures